The construction of an alternator for generating the required electrical power for an automobile and which functions as the drive source for the automobile engine is disclosed, for example in Japanese patent publication No. Toku Kai Hei 7-139550. FIG. 1 shows the alternator 1 that is described in this publication. A pair of rolling bearings 4 supports the rotating shaft 3 inside the housing 2 such that it rotates freely. There is a rotor 5 and a commutator 6 in the middle section of this rotating shaft 3. Also, a follower pulley 7 is fastened to the portion on one end (right end in FIG. 1) of the rotating shaft 3 that protrudes outside the housing 2. When installed in the engine, there is an endless belt that extends around this follower pulley 7 such that the engine can freely drive the rotating shaft 3 by way of the crankshaft.
Typically, a follower pulley that was simply fastened to the rotating shaft 3 was used as the follower pulley 7. However, in recent years, various kinds of pulley apparatuses with built-in one-way clutches have been proposed and used in some applications, by which power is freely transmitted to the rotating shaft from the endless belt when there is a tendency for the running speed of the endless belt to be constant or accelerating, and where the follower pulley and rotating shaft rotate freely relative to each other when there is a tendency for the running speed of the endless belt to be decelerating. For example, a pulley apparatus with built-in one-way clutch having this kind of function has been disclosed in Japanese patent publication Nos. Toku Kai Hei 10-213207, Toku Kai Hei 10-285873, Toku Kai Hei 11-22753 and Toku Kai Hei 11-63026. Also, the use of a roller clutch as the one-way clutch has been known previously and has been disclosed in the aforementioned publications.
FIG. 2 to FIG. 6 show a conventional pulley apparatus with the built-in roller clutch as described in these publications. This pulley apparatus with built-in roller clutch has a sleeve 8, which is a shaft member (rotating shaft member) that can be fitted and fastened onto the rotating shaft 3 of the alternator 1 (see FIG. 1). Also, the follower pulley 7a which is a pulley member is located around this sleeve 8 such that it is concentric with the sleeve 8. Moreover, a pair of ball bearings 9 and a roller clutch 10 are located between the outer peripheral surface of the sleeve 8 and the inner peripheral surface of the follower pulley 7a. 
The sleeve 8 is shaped generally in a semi-cylindrical shape, and fitted onto and fastened around the end of the rotating shaft 3 of the alternator 1 such that it rotates together with the rotating shaft 3. Accordingly, in the example shown in the figures, a screw hole section 11 is formed in the middle section on the inner peripheral surface of the sleeve 8, such that this screw hole section 11 can screw together with the male screw section formed on the outer peripheral surface on the tip end of the rotating shaft 3. Moreover, a fastening hole section 12 having a hexagonal-shaped cross section is formed on the tip end (left end in FIG. 2) on the inner peripheral surface of the sleeve 8, so that the tip end of a tool such as a hexagonal-shaped wrench can be fastened to the fastening hole section 12. Furthermore, the base end (right end in FIG. 2) on the inner peripheral surface of the sleeve 8 is a circular hole section 13 into which the middle of the tip end of the rotating shaft 3 can be fitted with no play therebetween. A spline joint, non-circular joint, key joint or other construction can be used as the construction for ensuring that there is no relative rotation between the sleeve 8 and the rotating shaft 3 in combination. Also, the center section of the outer peripheral surface of the sleeve 8 is a large-diameter section 14 that has a larger diameter than the other sections.
On the other hand, the tip end half of the outer peripheral surface of the follower pulley 7a has a wave-shaped cross section in the width direction, around which part of an endless belt called a poly V-belt extends. Also, the roller clutch 10 is located in the middle section in the axial direction of the space that exists between the outer peripheral surface of the sleeve 8 and the inner peripheral surface of the follower pulley 7a, and there are ball bearings 9 that are located near the opposite ends in the axial direction of this space such that they are located on both sides in the axial direction of the roller clutch 10.
Of these parts, the ball bearings 9 support both radial loads and axial loads that are applied to the follower pulley 7a, and allow the follower pulley 7a to rotate freely with respect to the sleeve 8. Each of the ball bearings 9 comprises: an outer race 16 that has a deep-groove type outer-ring raceway 15 formed around its inner peripheral surface; an inner race 18 that has a deep-groove type inner-ring raceway 17 formed around its outer peripheral surface; and a plurality of balls 19 that are located between the aforementioned outer-ring raceway 15 and inner-ring raceway 17 such that they roll freely. Also, the outer races 16 are fitted around the inner peripheral surface near the opposite ends of the follower pulley 7a, and the inner races 18 are fitted around the outer peripheral surface near the opposite ends of the sleeve 8. Moreover, in this state, one of the surfaces in the axial direction of each of the inner races 18 comes in contact with one of the opposite end surfaces (stepped surfaces) in the axial direction of the large-diameter section 14, respectively. In addition, the openings on the opposite ends of the space where the balls 19 are located are covered by seal rings 20 placed between the inner peripheral surfaces on the opposite ends of the outer races 16 and the outer peripheral surfaces on the opposite ends of the inner races 18.
Moreover, the roller clutch 10 transmits rotation force between the follower pulley 7a and the sleeve 8 only when there is a tendency for the follower pulley 7a to rotate in a specified direction with respect to the sleeve 8. In order to construct this kind of roller clutch 10, the inner clutch ring 21 is fitted onto and securely fastened around the large-diameter section 14 of the sleeve 8 through interference fit. This inner clutch ring 21 is made of carburized steel plate or the like and formed into a cylindrical shape by plastic processing such as pressing, and a cam surface 22 is formed around its outer peripheral surface. In other words, as shown in FIG. 3 and FIG. 5, by forming a plurality of concave sections 23, called the ramp section, at uniform intervals in the circumferential direction around the outer peripheral surface of the inner clutch ring 21, the outer peripheral surface is able to function as the cam surface 22. In the example shown in the figures, a tapered, concave chamfered section 24 is formed on one end (right end in FIG. 2) on the inner peripheral surface of the inner clutch ring 21, and this chamfered section 24 functions as a guide surface when fitting the inner clutch ring 21 on the outer peripheral surface of the large-diameter section 14.
On the other hand, an outer clutch ring 25 is fitted into and securely fastened around the middle section of the inner peripheral surface of the follower pulley 7a, and at least the middle section in the axial direction of the inner peripheral surface of the outer clutch ring 25 that comes in contact with rollers 26 (described later) is a simple cylindrical surface. This outer clutch ring 25 is also made of carburized steel plate or the like and is formed entirely into a cylindrical shape by plastic process such as pressing. Provided on the opposite ends in the axial direction of the outer clutch ring 25 are ring sections which form inward facing rim sections 27a, 27b in a flange shape. Of these rim sections 27a, 27b, the rim section 27a (left rim section in FIG. 2) is formed in advance when manufacturing the outer clutch ring 25, so it has the same thickness as the cylindrical section of the outer clutch ring 25. On the other hand, the rim section 27b (right rim section in FIG. 2) is formed after the rollers 26 (described later) and clutch retainer 28 have been assembled on the inside in the radial direction of the outer clutch ring 25, so it is thin.
Also, the plurality of rollers 26, which together with the inner clutch ring 21 and outer clutch ring 25 make up the roller clutch 10, are held in place by the clutch retainer 28 which is fitted onto the inner clutch ring 21 such that it does not rotated with respect to the inner clutch ring 21, and such that the rollers 26 can roll and move a little in the circumferential direction. This clutch retainer 28 is made from a synthetic resin (for example, a synthetic resin such as polyamide 66, polyamide 46, polyphenylene sulfide in which glass fibers are mixed in an amount of about 20%), and as partly shown in FIG. 4, comprises a pair of ring-shaped rim sections 29, and a plurality of column sections 30 that connect both of these rim sections 29 to each other.
Moreover, the sections that are surrounded by the inner peripheral surfaces of the rim sections 29 and the side surfaces in the circumferential direction of the column sections 30 are pockets 31 for supporting the rollers 26 such that they can roll freely and displace a little in the circumferential direction. Also, as shown in FIG. 5, the fitting protrusions 32 are formed at a plurality of locations on the inner peripheral surface of the rim sections 29, and engaged with the concave sections 23 which are formed on the outer peripheral surface of the inner clutch ring 21, the clutch retainer 28 is mounted on the inner clutch ring 21 such that it is not capable of rotating relative to the inner clutch ring 21.
Also, as shown in FIG. 6, springs 33 are mounted on one of the side surfaces in the circumferential direction of the column sections 30 of the clutch retainer 28. The rollers are held in the pockets 31, and the springs 33 are mounted on each column section 30 and elastically press the rollers 26 in the same circumferential direction of the clutch retainer 28 (to the right or clockwise direction in FIG. 5) in the substantially cylindrical-shaped gap that is formed between the outer peripheral surface of the cam surface 22 and the inner peripheral surface (cylindrical surface) in the middle section of the outer clutch ring 25, toward the section of the gap where the width in the radial direction is narrower. In the example shown in the figures, plate springs that are formed by bending spring steel plate into a substantially triangular hook shape are used as the springs 33, however it is also possible to use plastic or synthetic resin springs that are integrated with the clutch retainer 28.
Also, the opposite end surface in the axial direction of this clutch retainer 28 come close to and face the inside surface of both rim sections 27a, 27b of the outer clutch ring 25, in order to prevent the clutch retainer 28 from moving in the axial direction. In addition to this construction for preventing the clutch retainer from moving in the axial direction, construction where a plurality of stepped sections that are formed on the outer peripheral surface of the shaft member such as the sleeve are engaged with part of the clutch retainer is known and has been disclosed, for example, in Japanese patent publication No. Toku Kai Hei 11-22753 and Japanese patent publication No. Toku Kai 2001-165201.
When there is a tendency for the follower pulley 7a and sleeve 8 to rotate relative to each other in a specified direction when using the pulley apparatus with built-in roller clutch that is constructed as described above, or in other words, when there is a tendency for the follower pulley 7a to rotate with respect to the sleeve 8 in a direction such that the springs 33 press the rollers 26 (to the right or clockwise in FIG. 5), respectively, the rollers 26 bite into the sections of the cylindrical gap where the width in the radial direction is narrower. The follower pulley 7a is not able to rotate relative to the sleeve 8 (locked state). On the other hand, when the follower pulley 7a rotates relative to the sleeve 8 in the direction opposite the specified direction, or in other words, when there is a tendency for the follower pulley 7a to rotate relative to the sleeve 8 in the direction opposite the direction that the springs 33 press the rollers 26 (to the left or counterclockwise in FIG. 5), the rollers 26 move back against the force of the springs 33 to the section of the cylindrical gap where the width in the radial direction is broader, and the pulley 7a is able to rotate freely with respect to the sleeve 8 (overrun state).
There are two reasons for using the pulley apparatus with built-in roller clutch for an alternator having the construction described above. The first reason is in order to extend the life of the endless belt. For example, in the case of using a diesel engine or a direct-injection type gasoline engine as the drive engine, changes in the rotational angular velocity of the crankshaft become large at low speed such as during idling. As a result, there are small changes in the running speed of the endless belt that extends around the drive pulley. On the other hand, the rotating shaft 3 of the alternator that is rotated and driven by this endless belt via the follower pulley does not change so rapidly due to the inertial mass of rotating shaft 3 and the rotor that is fastened to it. Also, when the follower pulley is simply fastened to the rotating shaft, there is a tendency for rubbing to occur between both the endless belt and the follower pulley due to the changes in rotational angular velocity of the crankshaft. As a result, stress in differing directions is repeatedly applied to the endless belt that rubs with this follower pulley, making it easy for slipping to occur between the endless belt and the follower pulley, or causes the life of the endless belt to become shortened.
Here, by using a pulley apparatus with built-in roller clutch for an alternator as the follower pulley mentioned above, rotational power is freely transmitted from the follower pulley to the rotating shaft 3 when there is a tendency for the running speed of the endless belt to be constant or accelerating, and in contrast, there is relative rotation between the follower pulley and rotating shaft 3 when there is a tendency for the running speed of the endless belt to be decelerating. In other words, when there is a tendency for the running speed of the endless belt to be decelerating, the rotational angular velocity of the follower pulley is slower than the rotational angular velocity of the rotating shaft, and thus it is possible to prevent strong rubbing at the area of contact between the endless belt and follower pulley. In this way, direction of the stress that acts at the area of rubbing between the follower pulley and endless belt is made constant, and thus it is possible to prevent slipping from occurring between the endless belt and the follower pulley, and prevent the life of the endless belt from decreasing.
The second reason is for improving the electrical generation efficiency of the alternator. The rotating shaft 3, to which the alternator rotor is fastened, is rotated and driven by the drive engine of the automobile via the endless belt and follower pulley. When a fixed type follower pulley is used and the rotational velocity of the drive engine suddenly drops, the rotational velocity of the rotor also drops suddenly, and thus the amount of electric current generated by the alternator also drops suddenly. On the other hand, by using a pulley apparatus with built-in roller clutch for an alternator as the follower pulley for the alternator, the rotational velocity of the rotor decreases gradually due to the inertial force even when the rotational velocity of the drive engine drops suddenly, and electrical generation also continues during that period. As a result, in comparison to using the fixed type follower pulley, it is possible to more effectively utilize the kinetic energy of the rotating shaft and rotor, and increase the amount of electrical current generated by the alternator.
The explanation above was made for the case of installing the pulley apparatus with built-in roller clutch on the side of the follower pulley; however, similar function and results are also obtained when the pulley apparatus with built-in roller clutch having the similar constructions as described above is installed on the end of the crankshaft on the drive side.
In the various documentation in which the conventional construction for a pulley apparatus with built-in roller clutch was been disclosed, construction for maintaining the durability and reliability of the pulley apparatus with built-in roller clutch, and the method for efficiently assembling the pulley apparatus with built-in roller clutch were not specifically disclosed.
Taking the above problems into consideration, it is an object of this invention to provide a pulley apparatus with built-in roller clutch that is capable of maintaining sufficient durability and reliability, and provide a method for assembling the pulley apparatus with built-in roller clutch easily.